This inventions relates to methods and apparatus for interfacing a device to a set of push button inputs, and more particularly to methods and apparatus for interfacing a CT scanner to a network to create a safe and efficient user interface for accepting push button inputs.
In at least one known computed tomography (CT) imaging system configuration, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements, i.e., projection data, from the detector array at one gantry angle is referred to as a xe2x80x9cviewxe2x80x9d. A xe2x80x9cscanxe2x80x9d of the object comprises a set of views made at different gantry angles, or view angles, during one revolution of the x-ray source and detector. In an axial scan, the projection data is processed to construct an image that corresponds to a two dimensional slice taken through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered back projection technique. This process converts the attenuation measurements from a scan into integers called xe2x80x9cCT numbersxe2x80x9d or xe2x80x9cHounsfield unitsxe2x80x9d, which are used to control the brightness of a corresponding pixel on a cathode ray tube display.
Additional operator inputs to CT systems have been provided as CT systems become more and more flexible. The provision of additional push buttons on the gantry of the CT system to accommodate new functions has resulted in an increased number of cables. Although hard-wired connections to push buttons provide both speed and safety in operation, increased cabling requirements pose additional construction and material costs. In addition, cable routing problems occur due to the size of the required cables.
It would therefore be desirable to provide methods and apparatus to accommodate the need for additional push buttons on CT scanning systems without requiring large, costly cables, without compromising the safety and speed of a hard-wired connection.
There is therefore provided, in one embodiment, a method for efficiently and reliably communicating button presses electronically on a network from one or more push button nodes each having at least one push button, to a master node. This method includes steps of: generating status messages indicative of a push button states at each of push button node; communicating the status messages to the master node via the network; determining, at the master node, the state of the push buttons at each of the push button nodes from the communicated status messages; and triggering a response of the master node, in accordance with the statuses of the push buttons determined from the communicated status messages.
The above described method accommodates the need for additional push buttons on CT scanning systems without requiring large, costly cables, without compromising the safety and speed of a hard-wired connection.